Process and apparatus for piercing and rolling tubes.



R. 0. STIEPEL. PROCESS AND APPARATUS FOR PIERGING AND ROLLING TUBESAPPLICATION FILED JULY 3, 1912.

Patented 0013.28, 1913.

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RALPH CHARLES STIEFEL, or ELLWOOD CITY, PENNSYLVANIA.

PROCESS AND APPARATUS FOR PIERCING AND ROLLING TUBES.

To all whom it may concern Be it known that I, RALPH CHARLES STIEFEL, ofEllwood City, Pennsylvania, have invented certain new and usefulImprovements in Processes and Apparatus for Piercing and Rolling Tubes,of which the following is a specification, accompanied by drawings.

The invention relates particularly to piercing solid steel and otherbillets in the heated state and rolling them out into tubes by means ofcross rolling bodies and a mandrel bar.

The prime object of the inventionis to ac-' complish the piercing androlling out of the heated billet in a single continuous and progressiveoperation with least loss of time consistent with a proper action uponthe billet, thereby preventing such loss of heat of the, metal as wouldresult in injury and commercially satisfactory way of making tubes fromiron or steel billets by a continuous operation, itis the customary, andprobably most approved, practice to first pierce the solid billet in apiercing mill, and then remove the pierced billet to a rolling mill,

and there roll out andelongate the'tube and reduce its wall thickness asrequired. In this practice a loss of time occurs when no actual work isbeingperfornied on the billet, and considerable cooling of the metalinevitably occurs. Either reheating of the billet is necessary beforethe completion of the rolling operation, or else the cooling of themetal results in great wear and tear in 40 tools and machinery, theexpenditure of ex cessive power and the production of undue andinjurious strains in the metal of the billet and in the finishing rolls.Additional treatment, such as annealing, may become. necessary by reasonof such strains in the billet.

The present invention provides for the piercing of the billet and crossrolling of the tube continuously and progressively in ing sets of "pairsof cross rollin bodies, the forces applied to the metal being such thatthe tubeis satisfactorily and rapidly formed without undue strains orundue ,wear and tear on. the 5 apparatus employed. I

Specification of Letters Patent.

Patented Oct. 28, 1913.

Application filed m a, 1912. Serial No. 707,502.

The invention will be readily understood from the following'description,and certain other features not heretofore mentioned will be apparenttherefrom.

In the drawings, Figure 1 is a diagrammatic longitudinal sectional planview of one preferred arrangement of rolling bodies and mandrel bar forcarrying out the improved process without expansion of the tube; Fig. 2is a side elevation of the same arrangement; Fig. 3 is a view similar toFig. 1, showing the arrangement where expansion as well as elongation ofthe tube is desired.

The housings, bearings, guides, driving connections, 'etc., which canmanifestly be added in a great variety of forms without affecting theinvention, are omitted,- as in many of the-patents in this art, for thesake of clearness of presentation.

' The terms billet and tube are employed in this specification to alarge extent interchangeably; and by the term roll pair or pair of rollsI do not mean to exclude groups of three or more rolls set around andactin upon the same cross section of the billet in place of twooppositely acting rolls. I r

In Figs. land 2, four pairs of overlapped disk-shaped rolls are shownacting pro-gres sively, and 'to a large extent simultaneously,

upon the billet or tube. The longitudinal or feeding component of thecross rolling motion is produced by raising the "axes of the rolls whicharehorizontal somewhat above the plane of the axis of the pass, which ishorizontal. The succeeding pairsof rolls have their axes raisedprogressively, so as to give progressively increasing longitudinalfeeding action. The rolls are shown slightly inclined from the ass, asvseen in the plan view, to allow su cient clearance between the billetand the inactive side of each roll.

It will be understood that other-shapes and arrangements of roll pairsmay be used to give the same'cross rolling and longitudinal feedingcomponents of motion as the rolls shown. The formv selected. forillustration is that which I prefer.

In Fig.1, the axes of the rolls are shown in full, but the rolls are each s ect ioned, as follows: At the portion in contact with the billet,the roll is sectioned in the plane of the axis of the pass, as atthe lin15-6 of roll is sectioned on the plane of the axis of the roll, as shownby the line 34 of Fig. 2. The section is, thefefore, taken on the line34c5-6. The rolls B, C, D, E, F, G and H are similarly sectioned. Thearrows in Fig. 2 show the direction of rotation of the rolls and thetube. The circles drawn in dash and dotlines correspond approximatelywith the path of mot-ion of the center of the contact surface of theroll against the billet.

At J is shown the mandrel bar lying along the axis jj of the pass andprovided with a point M. The mandrel is supported against end thrust,but is free to turn against a suitable abutment L, and is of such lengththat the tube may pass clear from the last pair of rolls withoutstriking the abutment.

The billet is first pierced under the cross rolling pressure of therolls A and B, which for this purpose, as will be Well understood,

should have faces which converge and then diverge in the longitudinalplane of the pass, as is illustrated in Fig. 1. Also, as will beunderstood, the mandrel point should be in serted between the rolls andsustained at approximately the position shown. Under the cross rollingpressure of the rolls A and B, the billet is plerced and forced over thepoint of the mandrel bar, and as soon as its forward end reaches thesecond pair of rolls C, D, it is by them subjected to cross rollingpressure upon the mandrel bar and the wall thickness reduced. Theserolls have rollin faces which are convex in the longitudmal plane of thepass and of such restricted extent lengthwise of the pass that they actto thin the wall and elongate the tube upon the mandrel bar, being aidedin so doing by the fact that their component of feeding motion is reaterthan the preceding roll pair, so that t ey tend to feed the metal of thetube more rapidly forward.

By the term convex I do not mean to exclude the angular form, as shownin the rolls A and B, but I prefer the continuous curves illustrated.

As the billet still further progresses and reaches the third pair ofrolls E, F, it is there subjected to cross rolling under convexsurfaces, preferably with an increased component of longitudinal rollingmovement or feed, in excess of that commensuratewith reduction of thecross sectional area of the tube, so that the tube is subjected to somelongitudinal tension in the interval preceding these rolls. Preferably,also, the convexity of the rolls E, F, is somewhat less than theconvexity of the rolls G, D, thereby mak ing less of a noticeable spiraldepression or groove in the outer surface of the tube. At-

rounded oii' margins of their working faces,

preceding them and following the rolls E, F.

It is desirable that the successive pairs of rolls be approached closelyto each other for several reasons, thereby decreasing the time and spaceintervals between the succeeding actions, and also increasing theduration of the simultaneous operation of adjacent pairs of rolls.

It will be seen that the piercing action is almost immediately followedby a progressive, and to a large extent simultaneous, cross rollingtreatment of the billet in a plurality of succeeding roll pairs in amanner to elongate and thin the tube, and subsequently, and to a largeextent simultaneously, the tube is subjected to continuous smoothingaction. This last action also insures a slight looseness of the tubeupon the mandrel bar, so that it may be readily re moved therefrom afterit leaves the last roll air.

Manifestly, the number of pairs of convex elongating rolls, such as C,D, and E, F, which it is desirable to employ, will depend .upon thedegree of elongation and reduction of wall thickness desired. Where theconvexity of the last pair of these rolls is not very pronounced, onepairof smoothing rolls G, H, is sufiicient to substantially smooth andfinish the tube.

It will be understood that the interval between the two rolls of a pairwhich determines the width of the pass and the consequent reduction ofthe external diameter of the tube by such pair will be diminishedslightly in the succeeding pairs of rolls from C, D to G, H, the degreeto which it is advisable to. reduce the wall thickness in a single pairof rolls depending, as the skilled operator will know, upon thetemperature and also upon the toughness and quality of the metalundergoing treatment. The longitudinal tension produced by thedisproportionate or excessive increase of the feed component, asexplained, may be much lessened or entirely absent where expansion inthe diameter, as well as elongation of the tube is desired orpermissible. v

The continuous process of progressively and simultaneously piercing,elongating and expanding the billet and reducing the wall thickness ofthe tube is illustrated in Fig. 3.

Preferably the rolls C, D,-E' and F will be somewhat fiatteuand lessconvex than where there is, to be no expansion, and the longitudinaltension produced by disproportionate increase of the feeding componentof succeeding roll pairs-may be much diminished ascompared with Figs. 1and 2, or may be absent. The mandrel bar P should have successivelyenlarged cylindrical portions Q and R of diameter to approximately fillout and fit the expanded interior of the tube after it leaves thepreceding pair of rolls as illustrated. In this expanding process,separation of the rolls of each pair will progressively increase tocorrespond with the increased external diameter of'the tube, allowing,however, for sufiicient rolling pressure upon and reduction of the metalagainst the mandrel bar as is desired in view of the temperature andquality of the metal being rolled.

. It will be understood that after the tube has been rolled, Whetherwith elongation only as in Fig. l, or elongation and expansion as inFig. 3, the tube and mandrel bar may be removed from the pass line andthe 'tube withdrawn from the mandrel bar.

Subsequently, that bar or another is again placed in the workingposition between the roll pairs ready for the piercing and rolling ofthe next billet.

lVhile all the rolls illustrated are disk-.

shaped, I wish to include by the expression rolls, when not otherwisequalified, barrel shapes, disk shapes, and other forms when arranged tocross roll and treat the metal as described.

I claim the following:

1. The continuous process of piercing and elongating billets comprisingpiercing the billet by subjecting it to cross rolling between crossrolling bodies and a mandrel bar, and as theibillet advances on themandrel bar progressively and simultaneously elongating the tube andreducing the wall thicknessby subjecting it to cross rolling pressure onthe mandrel bar at a plurality of portions of its length between aplurality of pairs of convex cross rolling bodies with progressiveincrease of the ratios of feeding to cross rolling speed components.

2. The continuous process of piercing and elongating billets comprisingpiercing the billet by subjecting it to cross rolling between crossrolling bodies and a mandrel bar, and as the billet advances on the mandrel bar progressively and simultaneously elongating the tube andreducing the wall thickness by subjecting it to cross rolling pressureon the mandrel bar at a plurality of portions ofits length between aplurality of-pairs of convex cross rolling bodies with progressiveincrease of the ratios of feeding to cross rolling speed components, andprogressively and simultaneously smoothing the exterior surface ofthetube by cross rolling pressure between surfaces that aresubstantially parallel with the axis of the pass. I

3. The continuous process of piercing and elongating billets comprisingpiercing the billet by subjecting it to cross rolling pressure betweenrolling bodies and a mandrel bar, and as the billet advances on the barprogressively and simultaneously subjecting it to cross rolling pressureby successive pairs of convex cross rolling bodies with progressiveincrease of the ratios of feedm Y to cross rolling speed components.

4. The continuous process of piercing and elongating billets comprisingpiercing the billet by subjecting it to cross rolling pressure betweenrolling bodies and a mandrel bar, and as the billet advances on the barprogressively and simultaneously subjecting drel bar progressively andsimultaneously elongating the tube and reducing the wall thickness andalso expanding the tube by subjectin it to cross rolling pressure on themandrel Tar ata plurality of portions of its length between a pluralityof pairs of convex crossrolling bodies, and passing the tube expanded byone pair of rolls ontoa larger diameter of the mandrel bar, where it iscross rolled by-the succeeding pair with an increase in the ratio offeeding to'cross rolling speed components. I

6. The continuous process of piercing and elongating billets comprisingpiercing thebillet by subjecting it to cross rolling between crossrolling bodies and a mandrel bar, and as. the billet advances on themandrel bar progressively v and simultaneously elongating the tube andreducing the wall thickness and also expanding the tube iii) bysubjecting it to cross rolling pressure on the mandrel bar at aplurality of portions of its length between a plurality of pairs ofconvex cross rolling bodies, passing the tube expanded by one pair ofrolls onto a larger diameter of the mandrel bar, where it is crossrolled by the succeeding pair with an increase in the ratio of feedingto cross rolling speed components,'and progressively and simultaneouslysmoothing the exterior surface of the tube by cross rolling pressurebetween surfaces that are substantially parallel with the axis of thepass.

7. Apparatus for piercing and elongating billets, combining a mandrelbar, means for holding said bar-against 'endwise thrust, and a pluralityof separate pairs of'cross rolling rolls arranged in series, one of thesaid pairs being set to act adjacent to the point of the mandiel bar andhaving rolling faces adapted for piercing a billet, and one or more. oftheasucceeding roll pairs being adapted for reducing the Wall thicknessand set to act upon the tubular portion of the piercecl'billet upon thesaid mandrel bar.

8. Apparatus for piercing and elongating billets, combining a mandrelbar, means for holding .said bar against endwise thrust, anda pluralityof separate pairs of cross rolling rolls arranged in series, one of thesaid pairs being set to act adjacent to the point of the mandrel bar andhaving rolling faces adapted for piercing a billet, and one 0r.more ofthe succeeding roll pairs being adapted-for reducing the Wall thicknessand set..to. act upon the tubular portion of the pierced billet upon thesaid mandrel bar,

{and .snioothing .rolls having rolling faces substantially fiat andparallel along the pass which are set to act upon the billet'as itprogresses. along the said mandrel.

9. Apparatus for piercing and elongating billets, combining a mandrelbar, means storev holding said bar against endWise thrust,and

a plurality of separate pairs of crossrolling rolls' arranged in series,one of the said pairs being set to act ad acent to the point of themandrel bar andzhaying rolling faces adapted for piercing a b1lli,-3.llCl one. or.

the said mandrel bar having one or more portions of larger diameterbetween the later roll pairs for acting on expanded portions of thetube.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses, this 29th day of June, 1912.

RALPH CHARLES STIEFEL.

Witnesses:

G. E. MoYnR, M. E. NOLAN

